The disclosure herein relates to an aircraft propulsion assembly comprising a turbofan engine having an air flow valve with a variable flow rate intended to supply air to a heat exchanger.
In a manner known per se, an aircraft propulsion assembly comprises a bleed air system in the area of the turbomachine engine in order to provide a supply of air to the systems which use air, for example such as the cabin air exchange and pressure regulation system.
In order to ensure that the temperature of the air at the exit from the bleed air system remains within the acceptable limits for the user systems, the bleed air system comprises a heat exchanger (PCE for precooler:cooler) allowing the hot air that is bled at the engine to be cooled thanks to the cold air that is bled in the secondary stream of air of the turbomachine. The cold air is bled by a system for the supply of cold air comprising an air inlet arranged in the secondary stream of air, a duct connecting the air inlet to the exchanger, and an air flow valve with a variable flow rate of the butterfly type. The butterfly or movable flap is positioned inside the duct and provides the possibility, by its rotation, for adjusting the rate of flow of the system for the supply of air depending on the requirements of the user systems.
It will be appreciated that such a system for the supply of air does not provide the exchanger with a rate of flow of cold air sufficient to enable the latter to cool the air that is bled at the engine in the case of a propulsion assembly having a turbomachine with a high dilution ratio.
A suitable solution for such propulsion assemblies would be to increase the exchange surface of the exchanger and the dimensions of the air inlet and of the duct. This solution is not viable, however, since the space available for the arrangement of elements inside a propulsion assembly is very limited. The need accordingly exists for a system for the supply of cold air that is more efficient while retaining substantially the same dimensions as the current systems.